System for Immobilizing Small Watercraft

ABSTRACT

A system and method for a large ship to immobilize malicious small watercraft comprises of an unmanned underwater vehicle. The vehicle can be launched immediately upon detection of the threat. When the watercraft comes close, preparing to start boarding attack, the vehicle either uses it&#39;s onboard propulsion or is towed with a cable to sneak up on the watercraft and deliver an immobilizing effect, such as a hard crash or a stalling entanglement, on the propulsion mechanism of the watercraft.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claim priority from provisional patent application No. 61/941,314, filed on Feb. 18, 2014

BACKGROUND

1. Prior Art

The following is a tabulation of some prior art that presently appears relevant:

U.S. Patents

Pat. No. Kind Code Issue Date Patentee 8,776,710 B2 2014-07-15 Gayton 8,256,336 B2 2012-09-04 Larkin et al. 8,552,282 B1 2013-10-08 Garcia et al. 8,720,361 B2 2014-05-13 DiBruno, Sr. et al.

U.S. Patent Application Publication

Publication Nr Kind Code Issue Date Patentee 20140041516 A1 2014-02-13 Brewer

Foreign Patent Documents

Foreign Doc. Nr. Cntry Code Kind Code Pub. Dt App or Patentee 2013072704 WO A1 2013-05-23 Stevens

2. Field of the Invention

The current invention relates to non-lethal defense system and means for ships to immobilize small watercraft.

BACKGROUND OF THE INVENTION

Modern day pirates use small watercraft to attack merchant ships by boarding and hijacking the crew and the ship. These activities pose serious threats to the safety of the crew. Merchant ships responded by hiring onboard security guards and operating with high uneconomical speed. It also drew large fleets of naval ships to patrol some areas. Even though they seem effective, these deterrents are expensive, and the way these ships operate are producing unwarranted pollution. Due to regional anarchy situation, the threat around some costs of Africa could remain for the foreseeable future. And furthermore, similar kinds of piracy had also increased in other areas of the world such as southeast Asia.

To counter this threat, there had been a few propeller entanglement or disabling systems proposed. U.S. Pat. No. 8,776,710 to Gayton (2014), a passive towed array of entanglement lines. This system might stop the first uninformed attacker. Once the pirates learned what this is, they could attack by destroying the supporting structure such as cutting the suspension cables. After all, its rigging is openly visible. Even just a few whacks with a knife at the entanglement lines can send them tumbling down dangerously toward the ship's own propeller.

U.S. Pt. No. 8,256,336 to Larkin et al. (2012), an entanglement device between two hulls as unmanned underwater vehicles. In one embodiment, the two hulls will be separately guided. The entanglement linkage between the hulls will create an interference very difficult for the guiding process to handle. Another difficulty for this guiding scheme is that, when the two hulls come close to the target, they need to each aim at the acoustic signal with a changing side angle. In another embodiment, the two hulls are connected to a third hull with a variable link. This could make the whole setup cumbersome and not agile enough to chase a moving boat. On top of these issues, for all the embodiments presented, the entanglement net is directly coupled to the hulls and both hulls are at the same depth as the entanglement net. This will have a high chance of hitting the watercraft with the hull itself. In case of a head on or sideway interception, such collision would be catastrophic, which is undesirable.

U.S. Pat. No. 8,552,282 to Garcia et al. (2013), an unmanned underwater vehicle in the form of a torpedo with a protruding rod or rods. This approach added excessive difficulty by chasing a not too big moving propeller with a very small rod. It is like trying to poke a fly in the air with a toothpick. We all know it is easier to hit a fly with a swatter, especially if we know where the fly is going. The last two patents discussed both added unnecessary difficulties to the task such that, even if they can be realized, their systems could still be too complicated for nonmilitary merchant crew to operate.

There are other passive barrier type of security setups such as razer wires or bulwark. These could either be circumvented or destroyed by force because the setups are visible to the attackers, showing where they are vulnerable. One can only hope to be a less desirable target with these measures.

What seems still lacking is an effective defense system that is easy enough to be operated by a trained merchant crew. It will be beneficial if we can provide a non-lethal and cost effective way to protect against pirate boats so that a ship can travel safely anywhere in the world.

SUMMARY OF THE INVENTION

The present invention provides an easy-to-operate and non-lethal way to immobilize small watercraft. It can be used to protect merchant ships from pirates trying to board using small boats. It can also be used for apprehension operation by law enforcement or for antiterrorism by the military. In accordance with the illustrative embodiments of the invention, a system for immobilizing small watercraft comprises an underwater vehicle equiped with a structure to deliver a crippling effect to the propulsion mechanism of the watercraft. The vehicle is either self propelled or towed with a winch system. The structure for delivering crippling effect is either an entanglement device or a bumper for ramming the propeller. The vehicle is maintain onboard the ship and deployed in the water as soon as the threat is detected.

In case of a pirate boarding attack, the vehicle is launced and set waiting close to the ship behind where the pirate boat is heading. As the boat is about to be running next to the ship, the vehicle is brought forward alongside the ship, engage the boat and immobilize it.

In cases for counter terrorism or law enforcement, the launched vehicle is guided to intercept and immobilize the target watercraft at a distance from the ship. The guiding can be done using a homing guidance onboard the vehicle or an inertial guidance, with tracking information provided by the ship.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a towed vehicle 100 in use as an illustration of the general method.

FIGS. 2A-2C depict an embodiment of a towed vehicle 100.

FIG. 3 depicts the first embodiment of a winch system.

FIG. 4A-4B depict another embodiment of a towed vehicle 300.

FIG. 5A-5C depict yet another embodiment of a towed vehicle 400.

FIG. 6A-6B depict the second embodiment of a winch system.

FIG. 7A-7B depict an embodiment of an unmanned underwater vehicle (UUV) 500.

FIG. 8A-8D depict the UUV 500 and a tether cable 124 in use.

FIG. 9A-9B depict another embodiment of UUV 600.

FIG. 10A-10G depict yet another embodiment of UUV 700.

DETAILED DESCRIPTION

One critical perception the current invention discloses is as follows. As the pirates try to board the ship, they will bring their boat side by side next to the ship. For this window of time, they turn themselves into an easy target. Based on this understanding, many approaches become feasible for immobilizing such a sitting duck pirate boat. The underwater vehicle for this situation only needs to move along a preset course next to the ship. Therefore, it can either be a towed body, somewhat like a paravane, or it can be a self propelled unmanned underwater vehicle (UUV), without a need for homing capability.

In a towed body configuration, the cable serves as a means for both driving and guiding. The vehicle may even further use the side of the ship as a guide so active steering is not required. However, remotely controlled steering may allow for some off-course chasing capability. The depth control mechanism can be preset as well for proper delivery of the crippling effect. To cover the length of the ship, the winch system is pulling the vehicle from close to the bow and uses a guiding arm adjustable for different draft conditions. When not in use, this guiding arm can be retracted or folded up to reduce drag. To be stealth, this arm is completely underwater. Advantage of this approach is a low cost, low maintenance vehicle.

In an UUV configuration, the vehicle has onboard propulsion and steering. This means minimal or even no modification to the hull of the operating ship—a factor likely more appealing for ships already in service. The UUV can be controlled remotely by manual adjustment in steering and propulsion. The depth control mechanism can be preset but might just as well be made adjustable. Even though in this configuration, a tether cable between the vehicle and the ship is not required, such a cable could provide many additional benefits. It allows the vehicle to conserve power while waiting for the attacker to approach. It can be used to help with retrieval of the vehicle after the mission. It can also serve as a restraint to ensure that the vehicle will not hit and damage the ship's own propeller. For better serviceability, the signal wire for remote control may be combined and built into this tether cable.

In some other cases, such as for smaller ships, ships with low freeboard, or defense against terrorist attack, it may not be a good idea to allow the malicious watercraft to come too close to the ship. While, in a law enforcement apprehension operation, the watercraft is likely fleeting. The embodiments in the UUV configuration can further include a guiding or even homing mechanism on board whereby the UUV can intercept the watercraft and immobilize it at a good distance form the ship.

A few additional features can be shared with both the towed vehicle and the UUV configurations. In some embodiments, a camera system is used to provide surveillance so the operating crew can stay in the safe citadel. The camera can be mounted at high spots on the ship such as by the bridge or on an unmanned aerial vehicle drone. To make the vehicle or UUV easier to be identified by the surveillance system, one or more light sources are mounted on some of the embodiments. These light souces only emit light invisible to the human eye so as to keep the adversaries uninformed. In some other embodiments, a motion control subsystem can be used to coordinate the steering and other functions. This control system can incorporate data such as water flow parameters around the ship. Position of the vehicle relative to the ship can, for example, be extracted from processing the surveillance image or using a sonar. It is within the capability for those skilled in the art to implement such a subsystem. By doing so, the system does not requires skilled steering, and the operation can be as easy as entering a position referenced to the ship and hitting a go button.

Referring now to the drawings and in particular to FIG. 1, the first embodiment of a system for immobilizing small watercraft in use is illustrated in a perspective view. Pirate watercraft 210 is approaching operating ship 200. Towed vehicle 100 is positioned under water for the strike. Tow cable 120, attached to vehicle 100, is driven by winch 130 and redirected by cable guiding arm 132. Winch 130 and guiding arm 132 are either inside ship 200 or under water so the complete system are out of sight from the pirates.

FIG. 2A depicts towed vehicle 100 as the first embodiment in a perspective view. In this embodiment, vehicle body 102 is shaped as a hydrofoil itself It is negatively buoyant. At the designed towing speed, the buoyancy balances with the hydrofoil lift to set vehicle 100 at proper depth. Bumper area 103 as part of vehicle 100 is toothed. Bumper edge 105 is also toothed. Tail fins 106 are simply fixed to body 102. Keel plate 104 stabilizes vehicle 100.

FIG. 2B is a bottom view of towed vehicle 100. The lopsided front of bumper edge 105 is for pushing the watercraft away from ship 200 after immobilizing it. One way to set the course for towed vehicle 100 is to allow the bank effect to push it against ship 200. Some roller fenders (not shown) can be added to body 102 in this case. FIG. 2C depicts a side view of towed vehicle 100 moving forward toward propeller 212 of watercraft 210. Keel plate 104 provides a low offset attachment point for tow cable 120. This offset positions tow cable 120 low enough to prevent it form the possibility of being impeded by watercraft 210.

As described earlier, vehicle 100 is deployed before watercraft 210 is anywhere near ship 200. Referring to FIG. 1, vehicle 100 waits by the stern. The operation can be simply hitting the start button at the right moment for the winch system to tow vehicle 100 toward the bow of ship 200. Vehicle 100 bumps and disables watercraft 210, pushes it away from ship 200, keeps going for other watercraft ahead or moves back to the stern area until all threat is cleared.

FIG. 3 depicts a sectional view of ship 200 at where winch 130 is located (refer also to FIG. 1). In this embodiment for a winch system, guiding arm 132 can be extended to the proper position. When not in use, it is retracted to reduce drag. Winch 130 is positioned above the waterline. Mounted at the tip of guiding arm 132, pulley 134 redirects cable 120. Two sets of this system are illustrated. On the left side, towed vehicle 100 is deployed in the water, with guiding arm 132 extended. One the right side, guiding arm 132 is retracted and vehicle 100 is on crain 202. Also shown here are cameras 204 mounted by the bridge for surveillance.

Referring now to FIGS. 4A and 4B. FIG. 4A depicts a perspective view of another embodiment as towed vehicle 300 with entanglement device 314. Main body 302 has two arms 306 which are shaped as vertical fins. Ultraviolet lights 307 are mounted on top of arms 306. Wings 308 are hydrofoils which provide lift to keep arms 306 at the correct posture. A plurality of strands 315 are attached to and form part of entanglement device 314. Strands 315 are designed for both propeller and jet drive intake to ensnare. Entanglement device 314 is coupled to arms 306 by holders 312, which provide a sideway pull to keep entanglement device 314 taut (e.g. grip with two groved wheels). FIG. 4B depicts a side view. Body 302 holds multiple pieces of entanglement device 314 in a roll, with weak links in between pieces. Depth control subsystem 310 is onboard body 302. Entanglement device 314 is positively buoyant such that it floats toward the water surface to form a shallow scooping net, ready to snare a propeller in its path. Therefore, remote control in depth change is not needed in this embodiment. Vehicle 300 deploys entanglement device 314 one piece at a time the same way as an automatic paper towel dispenser. When propeller 212 catches and yanks on entanglement device 314, it is allowed to break at the weak link and detach from vehicle 300. On board sensor and mechanism enable vehicle 300 to deploy one more entanglement device 314 and the system is ready to function again. The operation of vehicle 300 is similar to vehicle 100.

FIG. 5A through 5C depict yet another embodiment of a towed vehicle 400. In FIG. 5A, a perspective view, two hulls 402A and 402B form the main body, to which a top bumper area 403 and front bumper 405 are attached. Towing bracket 404 for tow cable 122 also serves as a connection port for control data wires. Rudder 406 and diving plane 408 are remotely controlled. Two light sources 407 are mounted on the hulls 402A and 402B. As further depicted in FIG. 5B, front view and FIG. 5C, side view, the depth control also includes ballast systems 410 and hydrofoils 412. In operation, as soon as watercraft 210 comes within range, towed vehicle 400 is maneuvered to be underneath propeller 212. After watercraft 210 steadied itself relative to the ship, vehicle 400 is brought upward to engage and grind away the propeller. This method is a low impack, gentler way to immobilize a watercraft. In this embodiment, at least the depth variation is remotely controlled. Cable 122 also houses the control signal link (e.g., a coaxial cable with steel strands forming a tension bearing shell with electrical wires in the middle). Front bumper 405 is added as an option for taking out watercraft quickly when hard pressed. It can be as simple as a wide bar, or multiple bars (as shown here) to accomodate variation in depth of propellers.

Another embodiment for a winch system is illustrated in FIGS. 6A and 6B as partial sectional views of ship 200. Guiding arm 138 folds in and out similar to a fin stabilizer, swings up and down and further comprising telescoping sections. Winch 136 includes an underwater cable spool. FIG. 6A depicts the stowed configuration with vehicle 400 stored on deck. FIG. 6B depicts the system deployed. As we have demonstrated, different forms for such a winch system can be designed to meet the needed functions, as those skilled in the art will be capable of. It is to be understood that the illustrated designs of winch systems are just examples.

FIGS. 7A and 7B depict UUV 500, which is an embodiment of a vehicle in the configuration of an UUV with an entanglement device. In FIG. 7A, a perspective view, UUV 500 has main body 502 in the form of a torpedo, equiped with propulsion 504, rudder 506, and diving plane 508. Tether cable 124 slacks off when propulsion 504 is driving the vehicle. Arms 512 hold entanglement device 514 higher than and behind body 502, while also keep it taut. The combination of arms 512 and entanglement device 514 is like an archery bow, wherein arms 512 are elastic. Preset strain on arms 512 allows them to keep the proper shape while under pressure from the water flow. Entanglement device 514 and strands 515 are similar to that used in vehicle 300. Here however, small buoys 516 are added to help it float. The coupling between arms 512 and entanglement device 514 is made weak in the front-to-back direction, such that it will break at the moment when entanglement device 514 gets snatched.

FIG. 7B depicts a side view of UUV 500. Watercraft 210 (partial) and it's propeller 212 are also illustrated for their relative position in depth. Main body 502 will clear watercraft 210 from underneath it. Even arms 512 are light and flexible, so UUV 500 can run fast without the risk of a detrimental collision or sinking of watercraft 210. Depth control subsystem 510 is indicated here onboard body 502. Tether cable 124 houses the signal link for the remote control. A coaxial cable with steel strands forming a tension bearing shell can be used. The signal link in the middle of cable 124 can use an electrical or fiberoptic cable. Cable 124 may further house electric wires for power, if UUV 500 is not using onboard power source (e.g., battery). Cable 124 is adjusted to be only slightly negatively buoyant such that, when being slack, it does not seriously interfere with UUV 500.

Referring now to FIGS. 8A through 8D, FIG. 8A depicts side view, and FIG. 8B front view, of UUV 500 just being deployed. Tether cable 124 connects ship 200 and UUV 500, holding vehicle 500 in position under tension. The length of cable 124 is limiting UUV 500 from reaching the propeller of ship 200. FIG. 8C depicts side view, and FIG. 8D front view, of UUV 500 moving toward watercraft 210. Tether cable 124 sinks and stay out of the way. Operation of UUV 500 is similar to that of vehicle 300, except it has only one entanglement piece.

FIGS. 9A and 9B depict UUV 600, which is another embodiment of a vehicle in an UUV configuration having a wide bumper area. FIG. 9A depicts a perspective view. Main body 602 is shaped also like a torpedo, with propulsion 604, rudder 606, light source 607, and diving plane 608. Attached on top of the front end of body 602, wing 612 has a hydrofoil profile to generate lift. Wing 612 is equipped with ailerons 614 to help with roll control, which can be driven based on sensor feedback. The main reason for Wing 612 is to provide a frame for setting up wide bumper area 603, which formed a slop to reduce shock of the impact, while the hight of the slop accommodates variation in depth of target propellers. The slots in bumper area 603 has spacings such that it is not necessary to use high relative speed for ramming. Rather, the structure chews up a propeller. Wing 612 is further reinforced with two braces 618. RF antenna 616 receives remote control signal from operating ship 200. FIG. 9B depicts a side view of UUV 600 and onboard depth control subsystem 610 is indicated.

The operation for UUV 600 to immobilize pirate watercraft is similar to towed vehicle 100, except that UUV 600 is self propelled and remote controlled through RF or other types of wireless signals. The advantage of this embodiment is no hull modification for ship 200, while a concern is the limited power and hence the endurance of the vehicle. Especially if a pirate watercraft takes a long time approaching. A temporary leash from above the deck of ship 200 can be used after launch, which is to be released when the pirate watercraft comes near.

Referring now to FIG. 10A through 10G, which is another embodiment of the vehicle as UUV 700 with an entanglement device that has more than one piece of entanglement material. FIG. 10A depicts a perspective view of UUV 700. UUV 700 is similar to UUV 500, with body 702, propulsion 704, rudder 706 and diving plane 708. The difference from UUV 500 is that UUV 700 has two sets of arms 712A and 712B and use optical cable 126. Arms 712A and 712B can rotate and fold in, each attached with entanglement devices 714A and 714B respectively. The operating sequence is illustrate in FIGS. 10B, 10D and 10F as side views and FIGS. 10C, 10E and 10G as top views. FIGS. 10B and 10C depict UUV 700 during initial approaching, where both arms 712A and 712B are folded in at a low angle to reduce drag. FIGS. 10D and 10E depict UUV 700 with entanglement device 714A deployed by raising and opening arms 712A. FIGS. 10F and 10G depict UUV 700 with entanglement device 714B deployed, after entanglement device 714A has been snared and released. The benefits of having multiple usage per vehicle per launch are more than cost savings. As pirate attacks were often carried out with multiple watercrafts, the operating ship needs to be prepared for attack by more than one watercraft on the same side of the ship. In some cases, operating two or more UUVs in a small area may be complicated and risky. Optical cable 126 is used in this embodiment as the link for control commands. It is reinforced and adjusted to be negatively buoyant to keep it out of the way.

As mentioned earlier, for small ships, antiterrorist or law enforcement, it is desirable to immobilize a watercraft much farther away from the operating ship. Embodiments such as UUVs 500, 600 and 700 can be used for such applications. Due to the reason that the entanglement devices and wide bumper areas allow a large margin of aiming error, a non-homing type of guidance system can be used on the UUVs. Means onboard the operating ship, such as sonar or visual surveillance, can be used to extract the position and velocity of both the UUVs and the watercrafts. Programs onboard the operating ship can then guide the UUVs with motion commands for interception. Of course, the UUVs can further include an onboard homing guidance mechanism, which is well known in the art.

As pointed out through detailed descriptions and illustrations, the advantages of the current invention are numerous. The presented methods greatly increase the prospect of success while being very simple to operate. The system takes advantage of stealth so the adversaries will not be able to counteract easily. It will achieve a speedy termination of the threat, while not putting the targeted personnel in danger. It does not add burden to the ship when no threat is present, and consumes only minimal energy during operation.

The current invention was illustrated with many embodiments in various forms and shapes. Simply mixing some of the featured components from different embodiments presented can easily provide more new ones. Therefore, it is clear to be understood that what the disclosure teaches are just examples, not to be taken as limitations. And, the scope of the present invention is to be determined by the following claims. 

What is claimed is:
 1. A system for immobilizing small watercraft, comprising: a towed vehicle, deployable from an operating ship upon detection of potential threat, a tow cable attached to said vehicle, a winch system such that said vehicle can be towed via said cable, to and fro, close to and alongside the starboard or port side of the operating ship, a depth-control mechanism that enable said vehicle to stay at a predetermined depth under water surface, a structure attached to said vehicle, capable of inflicting crippling effect to the propulsion mechanism of the watercraft, selected from the group consisting of a wide bumper area made of hard material for ramming the propeller of the watercraft, and an entanglement device that can stall the propulsion mechanism of the watercraft.
 2. The system of claim 1, further comprising a monitoring camera subsystem employed by the operating ship to safely provide real time surveillance for the system operation.
 3. The system of claim 1, further comprising at least one light source mounted on the vehicle wherein said light source only emits light invisible to the human eye, whereby said vehicle can be more easily monitored by the operating ship while keeping stealth.
 4. The system of claim 1 wherein said entanglement devise has more than one piece of entanglement material attached, whereby said vehicle can immobilize more than one watercraft during one deployment.
 5. The system of claim 1 wherein said depth-control mechanism includes a hydrofoil and a ballast system.
 6. The system of claim 1, further comprising a communication means for said vehicle to receive control commands from the operating ship, such as RF antenna, acoustic transducer, electrical, and optical cable.
 7. The system of claim 6, further comprising a steering mechanism.
 8. The system of claim 7, further comprising a motion control subsystem to coordinate said towing and said steering whereby a simplified control interface can be provided.
 9. The system of claim 6, further comprising a depth adjustment mechanism.
 10. A system for immobilizing small watercraft, comprising: an unmanned underwater vehicle (UUV), deployable from an operating ship upon detection of potential threat, comprising: an onboard propulsion subsystem, a depth-control mechanism that enable said UUV to stay at a predetermined depth under water surface, a steering mechanism, a communication means for said UUV to receive control commands from the operating ship, such as RF antenna, acoustic transducer, electrical, and optical cable, a structure attached to said UUV, capable of inflicting crippling effect to the propulsion mechanism of the watercraft, selected from the group consisting of a wide bumper area made of hard material for ramming the propeller of the watercraft, and an entanglement device that can stall the propulsion mechanism of the watercraft.
 11. The system of claim 10, further comprising a monitoring camera subsystem employed by the operating ship to safely provide real time surveillance for the system operation.
 12. The system of claim 10, further comprising at least one light source mounted on the vehicle wherein said light source only emits light invisible to the human eye, whereby said vehicle can be more easily monitored by the operating ship while keeping stealth.
 13. The system of claim 10 wherein said entanglement devise has more than one piece of entanglement material attached, whereby said vehicle can immobilize more than one watercraft during one deployment.
 14. The system of claim 10, further comprising a tethering cable between said UUV and the operating ship, whereby said UUV can conserve propulsion power while waiting for the target watercraft to come into range.
 15. The system of claim 10, further comprising a homing guidance subsystem to home in on the target watercraft.
 16. The system of claim 10 wherein said depth-control mechanism includes a hydrofoil and a ballast system.
 17. The system of claim 10, further comprising a depth adjustment mechanism.
 18. The system of claim 10, further comprising a motion control subsystem to coordinate said propulsion and said steering, whereby a simplified control interface can be provided.
 19. A method for immobilizing small watercraft, comprising: deploying an unmanned vehicle to be underwater nearby the operating ship; waiting for the moment when the small watercraft is coming close to run alongside the operating ship; maneuvering the vehicle toward the watercraft to deliver a crippling effect to the propulsion mechanism of the watercraft, said crippling effect is selected from the group consisting of damaging crash of the propulsion mechanism, and Stalling entanglement of the propulsion mechanism.
 20. The method of claim 19 wherein said maneuvering the vehicle toward the watercraft comprising moving the vehicle underneath the watercraft; and rising upward toward the watercraft. 